Heavy rainfall causes E.coli spike in Toronto

Following the flooding from the July 8th storm in Toronto, Toronto beaches reported record levels of E.coli. These spiked levels were caused by sewage overflowing into Lake Ontario.

But why did this happen?

It all involves Toronto’s sewage system and the problem they are having with the growing population.

Having built their sewage system decades ago, the system is reaching a point at where it cannot keep up with the amount of sewage being produced. The sewage system was designed so that rainwater and sewage go through underground pipes. The two are separated using a divider so that rainwater can flow back into the lake while sewage can be carried to the water treatment plant. On a regular day, the system works fine. Although on days where Toronto gets hit with lots of rain, the sewage mixes together with the rainwater and is sent back into Lake Ontario without getting treated. This results in high levels of bacteria and E.coli.

The flooding that happened about two weeks ago was especially bad. Lake Ontario Waterkeepers estimated that about one billion litres of sewage probably got into the lake.

This poses health risks for those swimming in the lake and for aquatic life, but you shouldn't let this stop you from enjoying the beaches. Toronto Public Health takes daily samples of the water from beaches across the city to ensure the water is safe to swim in. By checking which beaches are safe on days you want to go for a swim, you will be fine. For a list of safe beaches go to the City of Toronto Website.

The issue regarding Toronto’s sewage system is expected to worsen as the population increases. The city does plan to take action though by improving the system’s infrastructure using a twenty-five year plan estimated at $1.2 billion.

In the meantime, residents can expect high E.coli levels on days where it rains a lot. The only thing you can really do is check to see which beaches are safe before making your way to the water.